mini DA air sander problems

[El Donkey]

I bought one of those cheap 2/3" da air Sanders. Also bought some buffing foam pads for small areas my larger electric rotary won't go.

Now I'm not sure if its the compressor or sander but the thing whizzes around but the head stalls at the slightest pressure. Makes it unpredictable with a small sanding pad and useless for polishing?

My compressor has a 2hp motor and a 100l tank. Its old but little used and doesn't say what cfm it is.

The sander is whizzing along but the head stalls?

 

[brightspark]

what size pipes are u using and what is output pressure set to .even if u have a smallish comp while its up to full pressure it should run the sander

 

[rory1]

I was using a small die grinder last week to dress a burr on a large gear and had the same trouble, the compressor was huge, it turned out to be a 1/4 BSP fitting with a tiny bore causing an air restriction. Changed the fitting and the problem disappeared.

Hope this helps

 

[ben8vgte]

If you are polishing you want a slower speed one than just a high speed sander one, if you turn the air pressure down low enough to polish they just stall.

But have you tried a drop or two of air tool oil in it, somtimes the vanes stick down. Indeed I had a cheap one as well that was burred up inside from poor machining, has it ever worked properly?

 

[normspanners]

Are you sure it is orbiting and not just spinning there is sometimes a lock to make them into a rotory sander but they are very low powered in that mode

 

[inchpincher]

Make sure there isn't an adjustable air speed control on the tool, unlikely on cheap stuff but worth a look. Swap the pcl connector (or equivalent) as mentioned and give it a good oiling.

My experiance with the 15 or so air tools I own is that as the 'torque' of the motors increases in proportion to the price. Two cheap purchases have gone in the bin (a Silverline cutoff tool was particularly gutless) but expensive can also mean thirsty for air so know your compressor limits.

Here's a quick list off the top of my noggin of companies I am happy to recommend, search eBay for specific brands rather than ’mini DA sander', I've picked up bargains because people who don't know better will badly list secondhand tools as a 'Dynabrade 56800' etc. Reminds me of the guy who reportedly made a fortune by winning auctions where people had mis-spelt 'diamond' in the title... Anyway

Seco Beltit - Finger sanders
Dynabrade - palm sander
Snap on insulated (pt is the range I think) - die grinders with low vibration.
Chicago - trigger mini sander grinder roloc thing (not DA but quite useful for awkward grinding and surface prep)
Ushio - Japanese micro grinders, 60k rpm!

 

[langy]

I bought one of those cheap 2/3" da air Sanders. Also bought some buffing foam pads for small areas my larger electric rotary won't go.

Now I'm not sure if its the compressor or sander but the thing whizzes around but the head stalls at the slightest pressure. Makes it unpredictable with a small sanding pad and useless for polishing?

My compressor has a 2hp motor and a 100l tank. Its old but little used and doesn't say what cfm it is.

The sander is whizzing along but the head stalls?

The consume huge amounts of air, you would need somewhere in the region of 14cfm to keep them fed correctly, also they are not the correct thing for polishing really.

 

[normspanners]

There also could be an air filter before it goes into the on off valve they are normally wire gauze and get clogged the debris from dirty air lines etc

 

[El Donkey]

Had a play today and found it barely spins a 3" 2000 pad without stalling.

I assume they have some form of clutch or slip action as the vanes are clearly spinning but the head stalls very easily. I only bought it a few Weeks ago and this has been my first attempt at usi.g it. There are no adjustments that I can see. Not sure of the internal dia but its on a rubber hose.
I also have a Kobe die grinder which doesn.t run great so think air supply could be part of the problem.

 

[El Donkey]

How can I check air output? Get an inline pressure gauge and see if the pressure is dropping at the tool? the pressure gauge is on the compressor.